The present invention relates to a disc drive microactuator system, and more particularly to an improved technique for electrically connecting a transducing head to a suspension flexure in the disc drive microactuator system.
The density of concentric data tracks on magnetic discs continues to increase (that is, the width of data tracks and radial spacing between data tracks are decreasing), requiring more precise radial positioning of the head. Conventionally, head positioning is accomplished by operating an actuator arm with a large-scale actuation motor, such as a voice coil motor, to radially position a head on a flexure at the end of the actuator arm. The large-scale motor lacks sufficient resolution to effectively accommodate high track-density discs. Thus, a high resolution head positioning mechanism, or microactuator, is necessary to accommodate the more densely spaced tracks.
One promising design for high resolution head positioning involves employing a high resolution microactuator in addition to the conventional lower resolution actuator motor, thereby effecting head positioning through dual-stage actuation. Various microactuator designs have been considered to accomplish high resolution head positioning. Most of the microactuator designs generate relatively small forces, so that the stiffness of the portions of the microactuator associated with the moving part, or rotor, must be very low (have a very small spring constant). Similarly, if the electrical connections from the head to the flexure are made by direct wire connections, the lateral spring constant of the flexure, microactuator springs and wire connections must together be sufficiently low to permit lateral head movement to occur with the relatively small microactuation force provided. Existing flexure technology cannot achieve the required flexibility, and even if such a flexure were achievable, there would be a force bias problem generated by mechanical offsets introduced by the inherently imperfect alignment between the flexure and the slider during bonding of the flexible electrical interconnects between the flexure and the head. This would result in a position shift, or mechanical bias of the microactuator from its center position. Since the total lateral stroke of the microactuator is typically on the order of 0.5 to 20 micro-meters (xcexcm), and the force generated by the microactuator becomes non-linear near the limits of the stroke, any bias greater than a fraction of the microactuator stroke degrades the performance of the disc drive, yet is extremely difficult to avoid if the electrical interconnects are attached directly between the head and the flexure.
There is a need in the art for an improved head to flexure electrical interconnect in a disc drive microactuator to alleviate the above-described deficiencies in the current state of technology.
The present invention is a disc drive implementing a dual-stage actuation system with an improved technique for electrically interconnecting the transducing head and the disc drive flexure. The disc drive includes a recording disc rotatable about an axis, a slider supporting the transducing head for transducing data with the disc and at least one bond pad electrically connected to the transducing head, and the dual-stage actuation assembly supporting the slider to position the transducing head adjacent a selected radial track of the disc. The dual-stage actuation system includes a support structure supporting the slider in proximity to a surface of the disc. The support structure is coarsely positionable by a main actuator. A microactuator is also included, with a stator attached to the support structure and a rotor operatively attached to the slider. The rotor is connected to the stator by at least one flexible beam. A first electrical interconnect is formed between the support structure and the stator of the microactuator. A conductive trace is formed on the flexible beam between the stator and the rotor of the microactuator. A second electrical interconnect is formed between the rotor of the microactuator and the at least one bond pad. By electrically connecting the support structure to the stator of the microactuator, where lateral stiffness is not a critical factor, the electrical interconnection scheme does not inhibit the lateral movement of the slider and transducing head by the microactuator. The electrical interconnect between the at least one bond pad and the rotor of the microactuator maybe formed by bonding a leg of a metal lead frame to the bond pad, bending and shaping the metal lead frame to contact a first conductive region on the rotor of the microactuator, and bonding the metal lead frame to the first conductive region on the rotor. The method of forming the electrical interconnect according to the present invention may be carried out at the slider level or on a bar of sliders cut from a wafer substrate.